Grinding fixture



B. J. TROCKI GRINDING FIXTURE Oct. 31, 1950 2 Sheets-Sheet 1 Filed Jan. 15, 1946 FIG. 2.

BERNARD J. TROCKI,

FIG. 4-.

Oct. 31, 1950 Filed Jan. 15, 1946 B. J. TROCKI GRINDING FIXTURE 2 Sheets-Sheet 2 amen H30 BERNARD J. mocm,

Patented Oct. 31 1950 UNITED STATES PATENT OFFiC-E GRINDIN G FIXTURE Bernard J. Trocki, Erie, Pa.

Application January 15, 1946, Serial No. 641,225

1 Claim.

A further object of the invention is to provide an improved work holding fixture for a surface grinding machine which enables the machine to be employed for precision thread grinding and for other precision grinding work.

Other objects and advantages of the invention will become apparent from the following description and claims, and from the accompanying drawings, wherein:

Figure 1 is a side elevational View, partly in cross-section, of a grinding fixture constructed in accordance with the present invention.

Figure 2 is a top plan View of the grinding fixture of Figure 1.

Figure 3 is a side elevational view of an arm employed at times to rigidly connect the work to the live center of the fixture of Figure 1.

Figure 4 is a plan view of the arm of Figure 3.

Figure 5 is a transverse cross-sectional View taken on line 55 of Figure 1.

Figure 6 is a transverse cross-sectional view taken on line 68 of Figure 1.

Figure 7 is a perspective detail view of a connecting pin member employed with the arm of Figure 3.

Figure 8 is a perspective view of a plate member employed to secure the live center of the grinding fixture of Figure 1 in position.

Figure 9 is a top plan view of the grinding fixture of Figure l, with the index plate positioned on the live center member for forming gear teeth.

Referring to the drawings H designates the base of the fixture, said base being adapted to be positioned on and secured to the work supporting table of a surface grinder, as by a conventional magnetic chuck arrangement. Base I i is provided with guide roller elements I2, l2 at its ri ht end, as viewed in Figures 1 and 2, for setting base H at a desired angle with respect to a reference shoulder on the grinder work supporting table, as, for example, by the use of a sine bar.

Base ii is formed with an upper longitudinal groove l3 and a bottom longitudinal groove M Which is wider than groove i3 and communicates therewith to form an inverted T-shaped groove. Positioned in groove I3 is a longitudinally slidable key member 45 having secured to the bottom thereof a wider key member it which is longitudinally slidable in bottom groove I i. Secured to key member l5 and longitudinally slid-able on the upper surface of base H is a wide carriage block H to the right end of which, as viewed in Figures 1 and 2, is secured a tail stock It and to the left end of which is secured a head stock iii. The carriage block has tWo spaced-apart, substantially parallel series of uniformly spacedapart holes 55 therein which series of holes extend longitudinally of the carriage block substantially from ne end to the other end thereof. The head stock and the tail stock are provided at their lower ends with apertured flanges 5t and 57, respectively, and cap screws or bolts 58 and 5% extend respectively through the head stock and tail stock flanges and are selectively engageable in the holes 55 to position the head and tail stocks at various selected distances apart. Rotatably mounted in tail stock i8 is a dead center member 20, said member 2%} being engaged at its end portion by a clamp element 2! which is threadedly engaged by a bolt member 22 passing through tail stock i8, whereby adjustment may be made of the pressure with which dead center member 26 engages the work piece. An adjustable bracket member 23 overlies dead center member 29 and engages the dead center member with a frictional force determined by the tightness of its adjusting bolts 24, 24.

Rotatably mounted in head stock i9 is a live center member 25, said live center member being held in position by a suitably apertured plate member 25 and having a hollow outer end 26 which is adapted to be rigidly secured as by' a drift pin 27 to the shank of a selected screw member 28 having the screw thread pitch which'it is desired to grind on the work piece. Screw member 28 is threadedly supported in a suitable bush- 7 ing 29 removably secured by a nut 29 to a vertical arm 30 which is rigidly carried by base H. Secured to the end of screw member 28 is a crank member 3! having a suitable handle.

Normally secured, as by set screws, to the inner end of live center member 25 in the position shown in Figures 1 and 2 is a circular index plate 32. Index plate 32 is formed with a plurality of equally spaced peripheral notches 33 and with a number of tapped holes 3 1, likewise equally spaced around plate 32 adjacent its periphery. Engaging the work piece, which may be a rod which is to be threaded such as rod 35 in Figures 1 and 2, is a clamp device comprising a notched arm 36 having adjustably secured thereto by bolts 31, 31 a notched jaw member 38, the work piece being clamp in the opposing notches of arm 36 and jaw member 38. Arm 36 carries at its .lower end a transversely extending member 39.

Member 39 is formed with an opening positioned under the main body portion of arm 36 in which is mounted a bolt member 49 carrying a plug element 4| having its end portion formed to enter any one of the openings 34 in index plate 32. A spring 22 biases plug member 4| toward its forward position. Transverse member 39 is formed with a threaded opening 43 whose purpose will be subsequently described.

In grinding a thread on to the work piece 35, base II is first positioned at the proper angle with respect to the plane of the grinding wheel. The grinding wheel is dressedto form the proper thread shape. The grinding wheel is then set so that its center is vertically aligned with the central axis of the work piece and is fed down on to the work. Crank 3| is then revolved clockwise, which moves the work in a manner corresponding to the threads on screw member 28, and thus forms similar threads on the work piece.

Where a multiple thread is to be ground, the first thread is formed as by the above described process. The work piece is. then returned to its starting position and plug 41 is shifted from its original aperture 34 of plate 32 to a suitable succeeding aperture of plate 32 corresponding to the angular displacement of the second thread with respect to the first thread at a given axial position on the work piece. The second thread may then be formed in the same manner as the first thread. Any desired number of threads may be formed on the work piece provided the number of apertures 34 is an integral multiple of the desired number of threads.

In forming gear teeth, screw member 28, Figure 2, is disconnected and index plate 32 is detached from the inner end of live center member 25, Fi ure 9, and is secured to the outer end of said live center member. Head stock l9 carries rigidl secured thereto a bracket member 44 having an arm 45 which is parallel to live center member 25. Arm 45 carries a plunger member 46 which is biased by a spring 41 into locking engagement with an opposing peripheral notch 33 of index plate 32 when said plate is secured to the outer end of the live center member 25. An arm 48, shown in Figures 3 and 4, is provided, said arm having an opening 49 adjacent one end thereof, which fits over the inner end of live center member 25 in place of index plate 32 and is adapted to be clamped thereto by a set screw 59. Arm 48 is formed with a slot which receives a pin member 52, shown in Figure 7, said pin member being threaded into opening 43 of transverse member 39. The gear blank is rigidly secured to a suit-' able shaft which is firml held between the live center member 25 and the dead center member 29 by the clamping members 35 and 38. The grinding wheel is appropriately dressed to form the desired gear teeth and base i l is set at the proper angle with respect to the plane of the grinding wheel. The grinding wheel is then fed across the periphery of the gear blank to form the first gear tooth groove. Plunger 46 is released and index plate 32 is rotated one or more notches (depending upon the desired width of the gear teeth) and plunger 46 is re-engaged therewith. The grinding process is then repeated to form the next gear tooth groove. In this manner all the gear tooth grooves are ground in the blank. It will be understood that the total number of notches in index plate 32 must be an integral multiple of the number of notches advanced for grinding each gear tooth groove.

The above described procedure may also be employed in grinding splines on shafts, equally spaced flats on cylindrical work, and the like.

The procedure mentioned above for grinding multiple screw threads may also be employed in grinding cutters. In grinding single threads, multiple threads, cutters and the like, it will be understood that a screw member 28 and bushing 29 will be selected so as to have the required pitch to conform with the thread to be ground.

While specific embodiments of a grinding fixture have been disclosed in the foregoing description, it will be understood that various modifications within the spirit of the invention may occur to those skilled in the art. Therefore it is intended that no limitations be placed on the invention other than as defined by the scope of the appended claim.

What is claimed is:

A portable work-holding fixture for mounting on a magnetic grinding machine table comprising a flat, elongated base having a slot of T-shaped cross section extending longitudinally thereof, an elongated carriage block slidable on the top surface of said base and having two spaced-apart, substantially parallel series of uniformly spacedapart, screw threaded holes therein extending longitudinally from one to the other end thereof, a T-shaped key slidable in said slot and secured t said carriage block to maintain the latter in operative assembly with said base, a head stock and a tail stock mounted on said carriage block, bolts engaging said head and tail stocks and selectively engageable in the holes in said carriage block to position said head and tail stocks at various selected distances apart, a live center member journalled in said head stock, and a dead center member carried by said tail stock opposed to and in longitudinal alignment with said live center member.

BERNARD J. TROCKI.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 286,663 Wheeler Oct. 16, 1883 986,688 Catucci Mar. 14, 1911 1,147,214 Cross; July 20, 1915 1,230,111 Callawa June 19, 1917 1,231,283 Mooney June 26, 1917 1,238,935 Olson Sept. 4, 1917 1,402,473 Bickford Jan. 3, 1922 1,662,078 Severson Mar. 13, 1928 I 1,669,919 Trbojevich May 15, 1928 2,251,885 Indge Aug. 5, 1941 2,367,957 Metcalfe 1- Jan. 23, 1945 

